This week, as this campaign reaches its midpoint, it's the second entry in our list from the nu-Who era and the first from Russell T Davies' tenure as showrunner - a chilling and claustrophobic tale that pushed the 10th Doctor to his very limit...

What's so fantastic about Midnight is that it feels like a great big middle finger from Russell T Davies to his critics - a spectacularly successful response to those who belittled his work, branding it "camp" or "silly" or "lightweight".

In 45 minutes, RTD subverts every supposed staple of his era as head writer and executive producer of Doctor Who - even placing the uber-confident, hyper-energetic 10th Doctor into a terrified paralysis.

Davies' writing is camp? 'Midnight' is pitch-dark - no pun intended. His stint on the show was too big or too broad or too silly? 'Midnight' is as stripped back as it gets - as fellow Who scribe Neil Gaiman once told Digital Spy: "'Midnight' was six people in a room, they just talk... there's something about that I just find so incredibly appealing."

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The episode not only subverts wider expectations of Davies' work, but also picks apart specifics - disassembling the 10th Doctor's persona, with his boisterous catchphrases mimicked, mocked and thrown back in his face. Most Doctor Who episodes take only a passing personal toll on our hero - 'Midnight' shakes him to his very core.

Davies' script forces David Tennant to move beyond the tics that had come to define his Doctor and the actor more than rises to the occasion. During his time on the series, Tennant played everything from heartbreak to impotent rage, but the look of fear in his eyes when the Doctor is paralysed, helpless, being dragged to his death, feels utterly genuine - it's one of his finest acting moments on the show.

Aside from shooting down his critics, Davies appeared to have one other big aim when sitting down to write 'Midnight' - to scare the bejeezus out of his audience. Forget the hoary old notion of 'kids hiding behind the sofa' - watching 'Midnight' alone in a dark and chilly living room on a June evening five years back, this writer will admit to feeling a little rattled.

One of the scariest things about Davies' script is that it leaves so much unexplained. When it comes to writing horror, a lack of motive on the part of the monster can actually prove far more chilling than supplying some cod explanation for its actions...

Every great horror film - from The Shining to The Exorcist to Paranormal Activity - has set the minds of its shaken viewers racing by steadfastly refusing to explain what the hell is going on and Davies fully embraces this trope.

What was the 'Midnight' monster? Was it targeting Sky? And if so why? And did it survive Sky's own demise? We never know for sure and it's so, so much better that way.

When you're making claustrophobic horror - with a small cast of characters trapped in an enclosed space - then it's also crucial that you hire a fabulous roster of actors. On this front, 'Midnight' does not fall short either - Tennant's phenomenal, yes, but there's not a weak link in the cast.

The three big reasons why 'Midnight' is so effective are Davies' taut script, Tennant, and Lesley Sharp's throughly unsettling performance as the tragic Sky Silvestry - transformed from sweet innocent to cold-eyed monster.

Also of note are Rakie Ayola as the episode's unlikely hero - the unnamed 'Hostess', Merlin's Colin Morgan in an early role as morbid, sarcastic teen Jethro and David (son of Patrick) Troughton, who delivers a distinguished performance as Professor Hobbes, despite stepping in for an injured Sam Kelly with just two days' notice.

Perhaps the only bad thing you can say about 'Midnight' is that you wouldn't want Doctor Who to be like this every week - part of why we love the show is its humour, its sense of fun, its joie de vivre.

But as a bleak, edgy one-off... it's very, very good indeed. Or as the Italians might say... Molto Bene.

Are you a fan of 'Midnight'? Does it deserve a place in our Doctor Who top 10? Share your thoughts below!